Составить вопросы к предложению. this little machine gave him a key to the invantion of the telephone.

Did this little machine give him a key to the invention of the telephone?
This little machine gave him a key to the invention of the telephone, didn't it?
What gave him a key to the invention of the telephone?
What did this little machine give him a key to?
Did this little machine give him a key to the invention of the telephone or the radio?